The sampling device according to the invention can be used for example to take fluid samples within the scope of oil or fluid pyrolyses in closed reactors. In order to be representative of the evolution of natural basins, these reactions last for several days or even several weeks. The kinetics of such reactions can be obtained according to two approaches.
The first approach, described for example by:
Ungerer P. et al, 1988, in Kinetic Modelling of Oil Cracking, Org. Geochem., 13, 857-868, consists in carrying out pyrolyses of increasing duration. At the end of each of the successive experiments, the kinetics is stopped by means of an abrupt temperature drop. The conversion coefficients and the reaction rates are thus acquired at different times. PA1 a sampling cell preparation stage comprising transfer of a certain volume of said material in the liquid state into said cell, suction of the fluid contained in the cell, transfer of said volume of material into the inlet of the cell and cooling thereof so as to form a sealed plug, and PA1 a sampling stage comprising communicating the sampling cell with a vessel containing the fluid to be sampled, and temporary heating of said plug (which leads to the melting thereof) in order to make it permeable to the fluid. PA1 it is economical while providing perfect sealing. The installation thereof is much simpler than that of a conventional valve. The installation simplicity thereof combined with its low cost, makes it possible to manufacture sample ampoules that can optionally be expandable. A batch of ampoules containing fluid samples representative of successive times of a reaction spread over a relatively long period can be readily constituted and it is therefore possible to simplify the organization of the stage of acquisition and processing of data relative to this reaction, which can last for a shorter time.
The other approach consists in performing successive samplings during the progress of a single experiment. Considering the duration of pyrolysis reactions, this approach has the advantage of reducing the total acquisition time. The entire kinetics can be obtained with a single handling whereas the number of experiments should be multiplied with the first technique. The method of operation through sampling also allows to check that the reactive medium has always had the same (thermal and therefore reaction) history in time, which is not always the case when experiments are repeated. On the other hand, using successive samplings requires a greater reaction volume in order to make sure that the sum of the various aliquots extracted in the course of time will not lead to considerable changes in the operating conditions of the reaction system. The implementation difficulty of this approach at high pressures is due to the considerable dead volume inherent in conventional needle valves.